If some of your kids are high school aged (especially 16-18), look into “dual enrollment” at your community college or a nearby college. This allows them to take a college level course in the area of their interest and get both high school credit and college credit. I don’t recommend more than one dual enrollment class per semester. Pick a subject that they are most interested in and you feel unqualified to teach.
On-line college classes are also available for dual enrollment, but I wouldn’t recommend them unless you have a near straight A student. I also wouldn’t recommend them for the first year of home schooling. They tend to be very intense and require initiative and excellent study skills.
Once a year, sign up for a standarized test. Although the SAT and ACT are designed for high school juniors, its not a bad idea to take one of them toward the end of the freshman and sophomore years for practice and to look for weak spots. Other tests are available for lower grade levels.
Ditto the college enrollment at a community college. It will give your kids a leg up and a well education 14-15 y.o. can easily handle the “college” work.
Our kids finished HS at around that age.